Advice on ordering custom synthetic peptides

I am after some advice on ordering custom synthetic peptides from commercial vendors. I've been getting quotes from a number of different companies and there seems to be a lot of variation and was wondering if anyone here has experience with this and could shed some light on the process. The best quote I have is from a Shanghai-based company called GLBiochem. Has anyone ordered peptides from this company before? The price is about 3 times lower than other companies have offered and one rep made the comment that they didn't know how they could charge so little without severely compromising quality so am a bit worried about that.

I asked the rep I was dealing with for information on their ISO certification and QC tests and he replied:

"Quality control of peptides is through MS (ESI probe) & HPLC which will be provided without charges." and they have ISO 9001:2008.

Having not ordered or made synthetic peptides before this is all a bit confusing for me so if there is anyone who is able to lend any advise on these matters it would be much appreciated.